A low-cost home-built NMR using Halbach magnet

Area of Science:

• Physics
• Chemistry
• Engineering

Background:

• Nuclear Magnetic Resonance (NMR) systems are crucial analytical tools.
• Traditional NMR systems are often large, expensive, and complex.
• There is a need for more accessible and cost-effective NMR solutions.

Purpose of the Study:

• To develop a low-cost, compact desktop NMR system.
• To leverage Halbach magnets for high field strength and small size.
• To enhance the mobility and signal-to-noise ratio (SNR) of the system.

Main Methods:

• Designed a 3-layer Halbach magnet with a wedge-shaped structure for rapid assembly.
• Performed magnetic field strength distribution simulations and calculations.
• Implemented passive shimming using magnetic blocks and steel pieces.
• Developed a compact single-board spectrometer with digital modulation and demodulation.
• Utilized a self-made probe for experimental testing.

Main Results:

• Initial magnetic field strength distribution aligned with theoretical predictions.
• Achieved an initial homogeneity of 576 ppm over a 5 mm square area.
• Improved homogeneity to 120 ppm after passive shimming.
• Demonstrated a spectral width at half-height of 20 ppm in a 1.5 mm diameter, 1 mm length cylinder.
• The compact spectrometer enhanced system mobility and SNR.

Conclusions:

• The developed desktop NMR system is compact and low-cost.
• The design utilizing Halbach magnets and passive shimming is effective.
• The system's features facilitate broader applications of desktop NMR technology.